Airplane with lifting fuselage, landing flaps, and quadricycle landing gear



Aug. 3, 1954 v. J. BURNELLI ET AL 2,685,420

AIRPLANE WITH LIFTING FUSELAGE, LANDING FLAPS, AND QUADRIGYGLE LANDING GEAR Filed Nov. 16, 1951 2 Sheets-Sheet 2 IN VEN TOR.

Patented Aug. 3, 1954 ALRPLANEWITH .LIFTING FUSELAGELAND- ING FLAPS, AND QUADRICYCLE LANDING Vincent J. Burnelli, Great Neck, N. Y., and :Hugh TJ.: Knerr, Annapolis, .Md.

nApplicationNovember 16,1951, Serial N0.1256,673

-T-his invention-is aan* improvement of the airv.-plane `disclosed in'vPatent V1;.9183688 issued on July :18, A1933, 'to 'Vincent J. urnelli, --and relates broadly -to the art of V`airplane landing gear `arrangements,1 and i-nV its more specic aspects it relates toa -quadricyclela-nding gear-'which retai-ns theadvantages-of vthe tricycle and'con- `vventioriallanding geararrangements'whilel eliminating the-disadvantages Which-are inherent in #both, andproduces furthersadvantages Aparticularly whenemployed with an airplanehaving a uwideairf oil bodyconguration or the liftingbody "type of des-ign for which it'- is lYparticularlywell l`adapted: and-the nature andobjects-of the in- 1 vention WillYbe-readilyrecognizedand-understood --by those skilled -in'thegarts to which it-'relates in the iight -of l' the f' following explanation and 'detaileddescription- --of theaccQmpan-ying :draw-ings illustrating what we at presentbelieveto"be' the `,preferred A embodiments-and mechanical expressions ,of our inventionAv from amongvarious other "forms, arrangements, combinations and con- ;structions, of Vwhich g the invention is capable Withinw the spirit and scope; thereof.

The -convcntionalgtype of landing gearprovides two main wheels and atal-wheel and is generally conceded to have; the followingadvantages:

(l) The main wheels @largest-rolling radius and strength are ahead of the CG andlead in .approaching roughor softterrain-'for operating under emergency eldconditions.

(2) "Reduced weight by Vcombining the tail wheel desgnleads Withgthetal group supporting structure and. requiring reduced critical` load 'design conditions.

(3) "The reardoor closer to thelground of adyvani'ageior loading facility- The disadvantages whichvare inherent in the conv,entionallanding gearare:

(A) inadequate, ground bearing .support ahead of the-ACGV to resist nosing .over tendencyfdue. to E:maximum usefoithe brakes, tor` stopping ,or'wheel drag caused by`v softfgroundor snowfespeciallyat i-lowgfspeedsfwithsmall air .pressure effectorl the longitudinal control surface- '.'lrhis iznoslng :over rhazard is -zamplined @with lare-.er @aircraft with greatly increased ioreward extension :of-theL body sectonfand heightfromnthe: ground.

:2 requiringvmore skilled and. carefulfpilot attention.

(C) yUndesirable `cargo` loadingwcondition vbecausefthe'cargo'/ floor is inclined ine-proportion" to `the angle-of the wings in relation to the'ground line necessary for high angle take-off attitude'of approximately 10 degrees.

The following .advantages are inherent in -tricycle type of landing gear:

(l) More directionally stable 'during ground roll because the center of gravity is ahead ofthe point of wheel drag and braking resistance.

This tends to keep the airplane-moving in a straight line, thereby relieving theground' looping v tendency which is= inherent yto the-conventional type,` and. reducing the` pilot skilly and conthe -trol attention under varied landing-and take-off conditions.

- (2) Level cargo floor because the airplane sets -at -about `zero angle instable groundsupport, desirable for 'best loadingy conditions and for improved pilots-taxying view.

(3) Theliftof the wings is nullied v-during ground 4roll providing increased wheel traction for rmaximum effectof'thebrakes with nosing over protection provided by thenose wheel.

-casefailure of -the tail-wheels gear is of minor consequence.

(B) The smaller nose Wheelof Ireduced rolling radius and bearing area leadsl into-rougher soft terrain,v and-must wiithstand overload conditions -dueY toghighy-braking action respecially necessary vfor blind'instrument landing approach conditions.

v (C) Increased weight-of' landing gear -and fiorward body structure with amplied-#wing torsional loads which increases the torsional'moment ofthe tractorengineY'mounts-whenheavybrake actionis applied. l

` (D) Increased heightX of the -rear -doorffrom theground which is not Edesirable for best loading conditions.

Wehave provided a` four-wheel orquadricycle -Vlandinggear which maintains the'iavorablequalities outlined above while eliminating the unfavorable qualities we have set forth. We have devised a new disposition of the landing wheels which permits maximum use of the brakes in landing operations with lift nullication and permits level loading which is obviously a highly advantageous and desirable result. While level loading is desirable for passenger airplanes it will be appreciated that it is particularly effective for cargo airplane design.

The landing gear arrangement of this invention has been designed to distribute the load so that approximately 60% is on the front wheels and 40% on the rear wheels when the airplane is standing.

The landing gear arrangement embodied in this invention having been designed particularly though not necessarily for a Burnelli type airplane which provides an air foil section body having a large cargo compartment is designed so that the landing gear when retracted does not interfere with this large and useful load area. This is a highly important factor of our design for it will be appreciated that reduction of cargo space would be uneconomical and highly objectionable.

Our unique quadricycle landing gear provides an airplane with readability and positive ground control generally -similar to that required for heavy four wheeled road vehicles with braking action also provided for the rear trucks to cause the resultant braking loads to act close to the center of gravity, thereby reducing the tendency to swing into a turn which is an objection to the conventional type of landing gear. It is to be understood'as will be fully clarified hereinafter, that the included angle between a line extending from the point of contact of the front wheel with the ground and the center of gravity of the airplane and a vertical line extending through the center of gravity of the airplane is approximately 35 degrees, this being in contrast to 17 degrees for a conventional type with a tail wheel of low bearing area and ground pressure. This increase in the angle over conventional types practically eliminates the danger of nosing over.

Our invention is particularly effective with the lifting body airfoil section or Burnelli type airplane, for with the level ground attitude for lift reduction and the provision of a level cargo floor close to the ground, the aerodynamic effect of the airfoil Ysection greatly increases the lift due to ground reaction during the take-01T and landing run. It is this contributing eiect of the airfoil section body which makes the combination of this type of body with the quadricycle landing gear highly advantageous and effective. For instance, the high ground reaction lift effect of an airfoil body section of thirty feet span which is about one-fourteenth of the body chord from the ground, creates high dynamic pressure which provides lift far in excess of normal lift requirements and tends to raise the airplane from the ground to relieve the high ground reaction pressure thereby automatically clearing the wheels of ground contact.

Another favorable factor iiowing from the combination of a quadricycle landing gear with an airplane having a wide airfoil body configuration resides in the provision of the required width and space for the mounting and retraction of the four wheel trucks.

Referring to the high ground reaction lift effect of the airfoil body section in the take-off of the airplane, we have provided means for amplifying this ground reaction effect tending to raise the airplane wheels clear of the ground for pressure relief prior to the airplane reaching take-on flying velocity. The means we employ consists of a special type of airfoil body iiap located in line with the rearwingspar bulkhead.

With the foregoing general objects, features and results in view, as well as certain others which will be apparent from the following explanation, the invention consists in certain novel features in design, construction, mounting and combination of elements, as will be more fully and particularly referred to and specied hereinafter.

Fig. 1 is a view in side section of the airplane.

Fig. 2 is a top plan view of the airplane, with parts thereof broken away.

Referring to the accompanying drawings we have used the numeral l to designate the airfoil section body of the airplane. Booms 3 carry the tail group designated generally by the numeral 5. In order to provide a low cargo floor ground relation and level, the center of thrust, or engines, has been raised to provide the necessary ground clearance as will be apparent from consideration of Fig. l of the drawings where the engines are indicated by the numeral 'I and the propellers by the numeral 9. Outspanned wings H extend from the lifting body which due to its airfoil configuration provides a large useful load area producing an airplane of great economies from either a commercial or military standpoint and wing flaps I3 are provided. It is desirable to employ the higha lift full span type of wing ap to provide the required angle of incidence for take-olf and landing conditions. This permits setting the wing lift angle at about 12 for take-off and 25 for landing, in relation to the thrust or ground line.

The quadricycle landing gear comprises a pair of front trucks I 5, each unit of which, in the disclosed example, consisting of a dual Wheel assembly, one unit being mounted at one side of the fuselage and the other at the opposite side thereof. The front trucks l5 are mounted on and supported from the No. 1 bulkhead i9 and are operatively mounted in any suitable manner to retract forwardly into a compartment l23 which is forward of the cargo space of the airfoil body and, therefore do not interfere with or consume cargo space. The landing gear also includes a pair of rear trucks I1, which are similar to the front trucks and are mounted on No. 5 bulkhead 2l and retract rearwardly into a compartment 25 which is rearwardly of the cargo space, the main cargo space being that area between bulkheads i9 and 2i. The landing gear is so mounted and constructed that when the airplane is at rest on the ground it is substantially level with the ground.

The rear trucks or wheels I'I constitute a main load gear, as contrasted with a conventional tail wheel. These rear wheels have two basic operating positions, securely locked or unlocked in swivel position. The rear wheels are always locked for the take-olf and landings at which time the front wheels are operating semi-swivel or with less than full castering but sufficient angular change for steering. Suitable control means are provided for controlling the operation of the wheels.

In the particular embodiment of our invention which is illustrated in the drawings, which is one example thereof, we have indicated the center of gravity at 21. The included angle defined by the line a which extends between the point of contact of the front wheel and the center of gravity of the airplane and the line b which is a vertical line extending through the center of gravity of the airplane is approximately thirtyve degrees, this being in contrast to approximately seventeen degrees for a conventional type with a tail wheel of low bearing area and ground pressure. This greater bearing area and ground pressure of the quadricycle gear provides more uniform tractional qualities necessary for straight line rolling stability and positive steering control when the brakes are applied for cross wind operation.

As pointed out an airfoil body flap 29 is provided which spans the airfoil section in line with the rear wing spar bulkhead 2|. This flap in extended position projects below the airfoil body section of the airplane and amplifies the ground reaction effect of the airfoil body in take-off by building up air pressure to clear the front of the airplane, and also augmente the effects of the wing aps I3.

On landing when making ground contact on the rear trucks the high ground lift reaction of the airfoil body section provides a beneficial high lift effect and being of gradual deceleration the nose will slowly lower and make cushioned contact on the forward trucks thereby stably supporting the airplane in level ground position and to employ full brake action during the landing roll.

It will be appreciated that the wide airfoil body employed for the Burnelli type of airplane is especially suited for the employment of the quadricycle landing gear arrangement of our invention. It permits maximum use of the brakes which are provided for the front and rear trucks and which are located fore and aft of the cargo or passenger section with no structural or wheel retraction interference.

We claim:

l. In an airplane in combination, an airfoil section fuselage, having outspanned wings, and a quadricycle landing gear for the airplane mounted on the airfoil section wherein the front wheels carry approximately 60% of the load when the airplane is standing and wherein the airplane assumes level ground attitude for level r cargo floor when standing, high lift full span wing flaps mounted on said outspanned wings and a ap mounted on the airfoil section fuselage and extending the full width thereof and extensible to position below and under said fuselage to amplify the high ground reaction lift effect 0f said airfoil section fuselage which provides lift in take-off of the airplane to relieve the high ground reaction pressure.

2. In an airplane in combination, an airfoil section fuselage having outspanned wings, and a quadricycle landing gear for the airplane wherein the front wheels carry approximately 60 per cent of the load when the airplane is standing and wherein the airplane assumes level ground attitude for level cargo floor when standing, high lift wing flaps mounted on said outspanned wings and a ilap mounted on the airfoil section fuselage forwardly of the rear wheel bearing points and extending the full width of said fuselage 7 and extensible to position below and under sa1d fuselage to amplify the high ground reaction lift 6 effect of said airfoil section fuselage which provides lift in take-off of the airplane to relieve the high ground reaction pressure.

3. In an airplane in combination, an airfoil section fuselage having outspanned wings extending from the upper portion of said fuselage, and a quadricycle landing gear for the airplane mounted on the airfoil section fuselage, the front wheels being pivotally mounted on a forward bulkhead in said fuselage at points substantially upwardly spaced from the lower surface of said fuselage and the rear wheels being pivotally mounted on a rear bulkhead in said fuselage at points substantially upwardly spaced spaced from the lower surface of said fuselage and said wheels when in ground engaging airplane supporting position being closely adjacent the lower surface of said fuselage to provide a low hung airfoil section fuselage, wherein the airplane assumes level ground attitude for level cargo oor when standing, high lift full span wing flaps mounted on said outspanned wings and a flap mounted on the airfoil section fuse- 1rage forwardly of the rear wheel points of ground contact and extending the full width of said fuselage and extensible to position below and under said fuselage to amplify the high ground reaction lift effect of said airfoil section fuselage which provides lift in take-oir of the airplane to relieve the high ground reaction pressure.

4. In an airplane in combination, an airfoil section fuselage having outspanned wings, and a quadicycle landing gear for the airplane wherein the included angle between a line extending between the point of contact of the front wheel with the ground and the center of gravity of the airplane and a vertical line extending through the center of gravity of the airplane is approximately 35 degrees, and wherein the airplane assumes level ground attitude for level cargo oor when standing, high lift wing flaps mounted on said outspanned wings and a flap mounted on and extending the full width of said airfoil section fuselage forwardly of the trailing edge thereof and extensible to position below said fuselage to amplify the high ground reaction lift eifect of said airfoil section fuselage which provides lift in take off of the airplane to relieve the high ground reaction pressure.

`ieferences Cited in the le of this patent UNITED STATES PATENTS OTHER REFERENCES Aviation Week, Papers 16 and 17, September 

